Chopped and spread maize stalks improve soil structure and fertility. However, because of the absence of research on airflow distribution in the chopping chamber, improvement of the spreading uniformity of chopped stalks has been limited. Therefore, in this study, computational fluid dynamics (CFD) technology was applied to analyze the influence of structural and operational parameters of the chopping and spreading machine on the velocity, pressure, and turbulent kinetic energy distribution of airflow in the chopping chamber. The experimental factors considered were the relative position angle (RPA) between the collecting-chopping shaft and the sliding-supporting shaft, working velocity (WV) of the chopping chamber, and rotational velocity of the collecting-chopping blade (RVCCB). The results revealed that RPA and RVCCB had a significant influence on the maximum negative pressure in the inlet (MNPI), the proportion of negative pressure area at inlet (PNPAI), and the maximum pressure drop at inlet and outlet (MPDIO). Additionally, RVCCB had a strong influence on the maximum velocity, average velocity, and velocity variation coefficient of airflow at the outlet. Moreover, maximum turbulence (MT) and maximum turbulent kinetic energy dissipation rate (MTKEDR) showed a positive relationship with RVCCB. To determine the values of RPA, RVCCB, and WV, a multivariate parameters optimization regression model was constructed, which yielded the optimal values of 15°, 1800 r/min, and 0.50 m/s, respectively. Subsequently, a hyperbolic spiral-type guiding shell with an arc length of 90° was designed to enhance the uniform distribution of airflow in the chopping chamber. Finally, a validation experiment of airflow distribution was conducted. The results showed that the velocity difference between the simulation and the validation experiment was less than 15%, indicating the accuracy of CFD simulation, and the spreading uniformities of the chopped stalks were better than national standards. These findings can serve as technical and theoretical support for the design and optimization of chopping and spreading machines.
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Air cushion belt conveyor is widely used in the transportation industry, but the related research on performance improvement stays in the theoretical aspect. For transportation equipment, it is necessary to balance the relationship between transportation efficiency and energy consumption. In order to improve transportation efficiency, increasing belt speed and increasing bandwidth are the main schemes to be considered. Improving the bandwidth requires changing the corresponding bracket to increase the cost of equipment renewal, compared with improving the band speed is the best research direction. The stability of the gas film is an important factor affecting the belt speed. When the belt speed is increased, the gas film needs to have stronger stiffness to resist the interference caused by fluctuations and high-speed movement of the conveyor belt. In order to solve these problems, we can improve the stiffness of the gas film and reduce the fluctuation caused by the device.
To improve the stiffness of gas film, it is necessary to study the influence of gas film formation factors by experiment. In order to reduce the fluctuation caused by the device, it is necessary to study the structure of the device itself. Fluctuations in installation accuracy are unavoidable. This paper proposes to install a pressure regulator in front of each gas chamber to reduce the fluctuation caused by different gas film parameters in the transport direction by reducing the numerical difference of input gas parameters in each chamber. Aiming at the research on the stability of the gas film, the experimental platform designed in this paper made the disc groove into a detachable form, and found the change law of the gas film stiffness by adjusting the air pressure, wind speed, porosity arrangement, aperture and hole spacing at the entrance of the gas chamber. To reduce the fluctuation caused by the uneven input flow parameters of the gas chamber; Aiming at the structure design of the pressure regulator, the feedback system composed of controllable venturi device is installed at the entrance of the gas chamber. Finally, the effect of the device on suppressing the gas film fluctuation is verified by external load impact experiment.
The experimental platform is equipped with a detachable slot. According to the theoretical design of different hole layout and hole spacing, the changes of the gas film were observed by changing the disk groove and adjusting the stomata parameters. A feedback system composed of controllable venturi device is proposed for the structural design of the pressure regulator, which can adjust the input flow parameters by adjusting the opening degree of the valve group. Finally, the experimental results show that when the belt is impacted by external load, the device can shorten the fluctuation time significantly by adjusting the input flow parameters.
The experimental platform designed in this paper is suitable for the experimental study of improving the conveying performance of the air cushion belt conveyor in the static state. The pressure regulator designed in this paper provides research ideas for the development of high-speed air cushion belt conveyor. At the same time, the experimental platform is helpful to improve the teaching quality of fluid and simulation-related subjects, and improve students' practice and innovation ability.
This paper designs an experimental test platform for visualization pulverizer. The platform adds frequency converter, servo motor, material level sensor and other devices, and installs the automatic adjustment control system of grinding roll rolling distance, which is more intelligent than the existing platform. The platform visualizes abstract knowledge and fills in the lack of teaching aids and practical operation in the course of grain machinery principle and design. The platform can assist the teaching of professional courses, stimulate students ' interest in learning, improve the learning effect, and closely link engineering with theoretical teaching. Based on this platform, students' engineering innovation and practical ability are improved, which provides strong support for cultivating innovative talents.
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